Carbon nanotubes (CNTs) have been used as fillers in elastomer matrices due to their unique mechanical and thermal properties. However, there is limited success in incorporating CNTs in cementitious matrices.
Generally, three major challenges are associated with the production of effective CNTs reinforced nano-composites. These challenges are: (1) maintaining large aspect ratio of the nanotubes, (2) good dispersion of the fillers in the polymer matrix, and (3) the interfacial adhesion between different phases. The large aspect ratio is necessary to maximize the surface area to achieve optimal load transfer from the polymer or cement matrix to the nanotubes. Due to the Van Der Waals attraction, nanotubes are held together as bundles and ropes. CNTs have very low solubility in solvents and tend to remain as entangled agglomerates. The agglomeration (entanglement) of carbon nanotubes in the elastomeric matrix diminishes the reinforcing effects. Therefore, effective use of CNTs in nano-composite applications depends on the ability to uniformly disperse the CNTs throughout the matrix without reducing their aspect ratio.
Polymer-modified concrete and polymer concrete are materials which involve concrete-polymer composites. They are made by partially or fully replacing the cement hydrate binders of conventional cement mortar or concrete with polymers, i.e., polymeric admixtures or cement modifiers, and by strengthening or replacing the binders with the polymers. This polymer concrete composite and mortars are currently used as popular construction materials. Polymer concrete has been used in the last 40 years in many applications ranging from bridge deck overlays, lining for sewer lines, to parking structures floors and in other structural applications such as machinery foundation and utility structures.
The use of different types of synthetic chopped fibers (5 mm length) in concrete composites has been suggested and has shown to slightly enhance the tensile and flexural strength of the concrete composites. However, dispersion of synthetic fibers in concrete composites is difficult due to the increased viscosity as compared to normal concrete. Additionally, synthetic fibers often enhance the crack arresting mechanism developed typically by the polymer film when hardened.
Thus, there is a need to overcome these and other problems of the prior art and to provide materials and methods for generating polymer-modified composites incorporating CNTs.